Ligula, Ligularius, Lingularius, Pharetra Lingula is a genus of brachiopods within the class Lingulata.

Lingula lives in burrows in barren sandy coastal seafloor and feeds by filtering detritus from the water.

The outer surface is covered by a thin glossy layer of protein called periostracum.

The shell of the young animal roughly remains the same, adding much material at the front and less at the sides.

The valves widen slightly at the front end, forming a narrow opening (or gape), through which water is pumped in at the sides and out from the middle.

In death, the gape is closed and the bristles may be absent or short as they become brittle and darker in color when dry.

At the rear end, that is deepest in the sea bed, the skin (or epithelium) secretes a glue-like mucus that binds to the substrate's particles, thus temporarily anchoring the animal.

[4] Lingula has long been considered an example of a living fossil; in fact, the perceived longevity of this genus led Darwin to coin this concept.

The cilia on the lophophore create a current through the mantle cavity, which ensures the supply of food particles and oxygen.

[2] Although Lingula is one of the most euryhaline brachiopods, it tolerates only moderate salinity variations (down to about half seawater salt concentration) and is optimally marine.